Photolithography has been widely used as a method for forming a high-resolution pattern used in electronic devices. However, photolithography is wasteful in terms of consumption of materials; is a multistep process; comprises a complicated process using a photomask, a photoresist, a developer and an etchant, thereby showing poor processing efficiency; and requires a large-area mask, resulting in poor applicability of a new design for photolithography to actual production lines. Therefore, in order to solve the aforementioned problems of photolithography, an ink-jet process has been developed as a method for forming a pattern directly onto a substrate without a mask, while minimizing the number of processing steps and waste of materials.
EP-A-O 880303 and Korean Laid-Open Patent No. 2004-28972 disclose a method for forming a pattern directly by way of an ink-jet process without a mask. FIG. 1 is a schematic flow chart for the method for forming a pattern by an ink-jet process. However, the above method provides too low of a resolution to be applied to microelectronic devices or the like. Also, the above method is problematic in that as the size of ink drops decreases, positional errors in a pattern increase relatively to the size of ink drops loaded onto a substrate, thereby causing a fatal open circuit or short circuit.
Additionally, Korean Laid-Open Patent No. 2000-5446 discloses a method for forming a pattern directly by using a laser. FIG. 2 is a flow chart showing the method for forming a pattern by using a laser patterning process. As shown in FIG. 2, an LTHC (light-to-heat conversion) material is coated onto a transfer film via a spin coating process or the like to form an LTHC layer (transfer layer); a composition, comprising functional materials and additives for controlling adhesion, is coated onto the top of the LTHC layer via a spin coating process or the like to provide a donor film; the donor film is adhered to a substrate; a pattern is transferred by laser irradiation; and then the donor film is removed after the transfer step to provide a high-resolution pattern. However, the aforementioned method is problematic in that a separate donor film is required, resulting in an increase in the cost; functional materials for patterning are coated totally onto the donor film, resulting in waste of functional materials; the additives added to the functional materials may cause degradation in the quality of the materials; interface between the donor film and the substrate may be contaminated upon the adhesion thereof; and the materials may be deteriorated due to high temperature generated by a laser.
Meanwhile, other patterning methods using a laser include laser ablation. However, a laser ablation process is problematic in that ablation efficiency for a particular laser wavelength depends on the quality of a pattern to be ablated; dose of a laser should be precisely controlled; and a pattern, substrate and a preliminarily formed pattern may be damaged upon the patterning of a multilayer structure.